Dice the onions, mash the garlic and mix both with the other ingredients for the marinade. Let the meat soak in the marinade in the roaster for a day, turning occasionally.
Turn the meat over again and add 1 cup of water. Cover and cook (with lid or aluminum foil) at 180 ° C for approx. 2 hours.
When the roast is done, remove the meat and cut into slices. Strain the sauce, season to taste and mix with a little cream or crème fraîche.
This goes well with spaetzle, white bread and cucumber salad.